Pressure switch



June 1936- E. F. MEKELBURG ,8

PRESSURE SWITCH Filed April 9, 1954 2 Sheets-Sheet 1 INVENTOR ATTORNEY wwg June 9, F, MEKELBURG 2,043,803

PRESSURE SWITCH Filed April 9, 1934 2 Sheets-Sheet 2 INVENTOR ATTORN 15 v having the double function of the direct trip- Patented June 9, 1936 UNITED STATES PRESSURE SWITCH Earl F. Mekelburg, Wauwatosa, Wia, assignor to Square D Company, Detroit, Mich.

Application April 9, 1934, Serlal No. 719,673

' 8 Claims. (01. 20o 1ss) This invention relates to pressure switches.

Objects of this invention are to provide a pressure switch which may be very cheaply built, which is very small, which has a small number of parts, and in which the main parts are formed from stampings and molded. insulation material, such as a phenolic condensation product.

Further objects are to provide a pressure switch in which a double pole construction is provided and which in one form of the invention may be provided with an electrical overload means for opening the switch irrespective of the pressure response mechanism, in which the overload device may be a self-soldering device, in which a reset means is provided, such reset means also ping means for the switch mechanism and guiding means for the switch operating members actuated from the pressure response member.

Further objects are to provide an overload pressure switch having a-reset construction which slidably passes through the body portion, which has a projecting reset part accessible without removing the cover to the mechanism, and in which the body portion and the reset slide form insulat ing portions which themselves constitute or provide insulating chambers within which the actual switch parts operate, thereby providing against inadvertent flashover, short circuiting or other defects.

Further objects are to provide a novel form of construction in which the stationary contacts retain the movable contacts in assembled position, in which the stationary contacts are so constructed that they are held by the same screw which constitutes a terminal or line receiving screw, so that only one screw need be used to furnish both the retaining means for the stationary contacts and-the attaching means for the conductors.

Further objects are to provide an overload attachment which is so made that a pawl nomially releasably heldby the self-soldering device is spring urged outwardly by the same spring means employed to raise the combined guide and overload release member, thereby reducing the number of parts to aminimum for this portion of the construction.

Further objects are to provide a construction in which an insulating body portion is provided with an internal cavity within which stationary and movable contacts are housed and are operated either by movable means projecting from the casing or by a movable guide which carries the movable means. The construction is such that the housing and the guide substantially house the contacts, the housing being completed by a cover member through which at least the movable members project, the housing providing for a double pole switch construction in which the separate units of the double pole switch are individually housed and are thus separated from each other by insulating partitions or portions of the housing itself.

This application is a continuation in part of my co-pending application for Pressure switches filed June 29, 1933, Serial No. 678,245;

An embodiment of the invention is shown in the accompanying drawings, in which:-

Figure 1 is a vertical sectional view of the device with parts broken away.

Figure 2 is a sectional view on the line 2-2 of Figure l.

Figure 3 is a sectional view on the line 3-3 of Figure 2.

Figure 4 is a perspective detail of one of the stationary contacts.

Figure 5 is a bottom plan view of he housing removed from the remainder of the apparatus, showing the stationary and movable contacts in place.

Referring to the drawings, it will be seen that the device comprises a flexible diaphragm l which is clamped between the bottom capsule or cupshaped member 2 and the body portion of the casing 3. The cup-shaped member 2 is provided with a hexagonal fitting 4 whereby it may be screwed upon a pipe to provide communication to the interior of the capsule 2 beneath the diaphragm, and also to support the device.

A head or diaphragm contacting plunger I rests upon the diaphragm, the casing 3 being cut out adjacent the diaphragm, as shown most clearly in Figure 1. The plunger or head 5 is provided with upstanding, pointed, spaced lugs 6 which seat within a socketed portion 1 of a lever 8. The lever 8, as may be seen from Figure 1, is a -channel-shaped stamping provided with shoultransverse supporting portion l5 upon which the insulating-body portion l8 rests and to which it is secured.

Preferably an insulating closure member or gasket 11, such, as fiber or other material, may be employed and positioned between the insulating body portion l 6, which may be of a phenolic condensation product or other insulating material, and the support l5 of the main frame member. The lever 8 is thus rocked by the diaphragm and its motion is resisted by an adjustable spring l8 held under compression by an adjusting nut l8 threaded upon a projecting stem 20. The stem 20 passes through the upper portion 2| of the casing and a thumb nut 22 servesto lock the upper portion of the casing in place, such thumb nut being carried by the stem 20.

The lever 8 constitutes one portion of a quick motion mechanism operated from the plunger for actuating the switch. It constitutes no portion of the present invention. It carries one end of a; spring 23, the other end of which is secured to a lever 24 which is provided with knife-edge portions 25 seated within the pointed portion of pear-shaped apertures 26 formed in the side walls of the frame I2. As the lever 8 is rocked upwardly, the plate 24 is suddenly snapped up wardly and upwardly moves downwardly projecting plungers 21 formed of insulating material, such as a phenolic condensation product or similar material, and carried by a movable guide 28 also formed of a phenolic condensation product or similar material.

As stated above, the quick motion mechanism and the fluid condition responsive means, such as the pressure control snap motion mechanism, forms no part of the present invention and is claimed in my co-pending application referred to hereinabove.

The body portion I6 is held to the support l5 by means of screws 29 whose heads are seated within relatively deep apertures 38 formed in the body portion, as shown most clearly in Figure 2.

The interior of the body portions is provided with a cavity 3|, as shown most clearly in Figures 2, 3, and 5. Within this cavity stationary contacts 32 are positioned and are arranged in pairs. These contacts are provided with contact points which engage the contact point carried by the movable contacts 33. These movable contacts 33 are in reality bars which are pressed towards or biased towards switch closing position by means of springs 34 whose upper ends are I seated within sockets 35 formed in the body portion, as shown most clearly in Figures 2 and 3.

The contact bars or movable contact members 33 are in eifect substantially individually housed as the body portion is provided with an inwardly projecting part 36, see Figure 5, and with inwardly projecting webs 31 which separate the two pairs of stationary contacts 32 and the movable contacts 33 from each other. Also, it is apparent that these groups of contacts are designed'for a two-pole switch and are widely spaced and consequently there is no chance of inadvertent arcing or connection between these contacts.

, The movable guide 28 is free to move and it is to be noted that it is provided with an upwardly projecting stem 38, see particularly Figure 1, which slidably passes through the rectangular aperture 39 formed in the body portion l6, as most clearly shown in Figure 1, the aperture being also clearly shown in Figure 5.

This movable guide which slidably carries the movable members or insulating plungers 21 is,

as stated, formed of insulating material itself and is provided with sockets which receive the upper heads 40, see Figures and 3, of the movable members or plunge-rs ill. These movable plungers are, therefore, held directly beneath theircorresponding movable Contact bars 33. It is to ha its ends positioned directlybeneath the movable 5 contact bars 33.

Thus when this slidable guide is itself moved upwardly in a manner hereinafter to appear, it is obvious that it will simultaneously lift both movable contact bars 33 and thus open the switch. 10

The means for actuating this movable guide is an electrical overload device 4|, see Figure 1, which may be of the self-soldering ratchet wheel type, which restrains the guide against upward motion, such guide being urged upwardly by 5 means of a small spring 42 located within a slotted portion of the guide. The upper end of the spring also bears against a small pawl 43 which engages the teeth of the ratchet wheel 4|. Obviously when the overload occurs and the ratchet wheel 20 is released as the soldered connection thereof is softened in a well known manner, it will rotate and allow the pawl 43 to move upwardly, thus permitting the guide to move upwardly. This, therefore, causes an opening of the 20 switch as the T-shaped head of the guide lifts the movable contacts of the switch from their stationary contacts. I

The switch is additionally operated by the quick motion fluid condition responsive means 30 hereinbefore described.

Referring now to the stationary contacts 32, it will be seen that these contacts are substantially U-shaped. They are provided with an upper terminal plate 44, as shown in Figures 2, 3, and 4. Their lower portions underhang the movable contact bars 33 and enter the cavity 3| of the body portion through notches or cut out portions 45, as shown most clearly in Figure 3. The upper terminal plate or member 44 of the station- 40 ary contacts is joined to the lower portion 32 thereof by means of an outer strip or arm 46 integral with both'portions.

It is to be noted that these stationary contacts straddle a part of the body portion l6, as shown 45 most clearly in Figure 2, and that a terminal screw or conductor receiving screw 41 passes through the upper aperture 48 formed in the terminal portion 44 of the stationary contact and has its lower threaded portion screwed into the 50 threaded aperture 48 formed in the lower portion of the stationary contact.- Thus one screw serves the double purpose of both holding the stationary contact in place and also acting as a terminal screw. In addition, the stationary contacts are 55 very securely positioned as they straddle a portion of the body portion 15 of the apparatus and also as their vertical arms 46 are positioned in slots or notches 50 formed in the body portion l6, see Figure 5.

These stationary contacts are thus very securely held in place against lateral or any other shifting motion, and in addition, a single screw performs the dual function of holding the stationary contacts in place in cooperation with the 65 body portion and also of providing a terminal screw for the conductors.

It is to be particularly noted that the movable and stationary contacts are completely housed by the body portion and the bottom gasket or clo- 70 sure member W. Additionally it is to he noted that'each pair of stationary contacts and its corresponding movable contact is electrically separated off from the other pair of stationary contacts and its movable contact by barriers formed 75 in the body portion. Additionally it will be seen upon reference to Figure 5, that this separating body which may be readily molded in a very cheapmanner and which provides a very small number of parts, all of which are readily accessible and easy to assemble.

It will be seen further that a very secure anchoring of the stationary contacts is afforded by this invention and that no auxiliary means need be provided for guiding the movable contact bars, as each is carried in its own appropriate channel like compartment in the body portion, which when all of the parts are assembled, are separated off from each other in a very substantial and effective manner. v

It is to be noted also that a very compact construction is provided in which all of the active electrical parts are housed in a remarkably constricted space, as is apparent from the detailed description hereinabove.

. Although the invention has been described in considerable detail, it is to be understood that the description is to be interpreted as illustrative rather than limiting, as the invention may be variously embodied and is to be determined only as claimed.

I claim:

1. In an electric switch of the class described, an insulating body portion, stationary contacts and terminal members straddlinga portion of said insulating body portion and having contact ends spaced from said body portion and located on one side of said body portion and having terminal clips located on the other side of said body portion, terminal screws for clamping conductors to the terminal members, said screws slidably passing through said body portion and threaded into said stationary contacts and engaging both said stationary contacts and terminal clips, said screws slidably passing through said terminal clips, a movable contact located between said body portion and said contact ends, a spring urging'said movable contact towards engagement with said contact ends.

2. In an electric switch of the class described,

said contact ends, and a spring urging said mov able contact towards engagement with said contact ends, said spring bearing at one end directly against said movable contact and at its other end against said insulating body portion.

3. In an electric switch of the class described, an insulating body portion, stationary contacts and terminal members straddling a portion of said insulating body portion and having contact ends spaced from said body portion, terminal screws for clamping conductors to the terminal members, said screws slidably passing through said body portion and threaded into said sta- 5 tionary contacts and engaging both said stationary contacts and terminal clips, said screws slidably passing through said terminal clips, a movable contact located between said body portion and said contact ends, a spring urging said movable contact towards engagement with said contact ends, said spring hearing at one end directly against said movable contact and at its other end against said insulating body portion, and an insulating. plunger slidably carried in alignment with said movable contact.

4. In an electric switch of the class described, an insulating body portion, stationary contacts and terminal members straddling a portion of said insulating body portion and having contact 20 ends spaced from said body portion, terminal screws for clamping conductors to the terminal members, said screws slidably passing through said body portion and threaded into said stationary contacts and engaging both said stationary contacts and terminal clips, said screws slidably passing through said terminal clips, a movable contact located between said body portion and said contact ends, and a spring urging said movable contact towards engagement with said contact ends, said body portion having a recessed part for said movable contact and for said contact ends, whereby an insulating housing is provided for said switch.

5. In an electric switch 01' the class described, an insulating body portion having an interior cavity, stationary contacts located 'within said cavity, a movable contact located within said cavity, a movable member projecting from said body portion for actuating said movable contact, and a movable guide projecting from said body portion for additionally actuating said movable contact, said movable member being movable with respect to said guide and said guide being mov- V able with respect to said body portion. 4

6. In an electricswitch oi the class described, an insulating body portion having an interior cavity, stationarycontacts located within said cavity, a. movable contact located within said cavity, a movable member projecting from said 50 body portion for actuating said movable contact, and a movable guide projecting from said body portion for additionally actuating said movable contact, said movable member being movable with respect to said guide and said guide being movable with respect to said body portion, said body portion and said guide enclosing the major portion of said contacts.

7. In an electric switch of the class described, an insulating body portion having an interior cavity open through one side of said body portion, stationary and movable contacts located within said cavity, an insulating closure member substantially closing the opening leading into said cavity, a guide located partly within said cavity 65 and projecting through said closure member and together with said closure member closing said cavity, and an operating member for said movable contact carried by said guide and projecting outwardly from said closure member. 7

8. In an electric switch of the class described, an insulating body portion having an interior cavity open through one side of said body portion, stationary and movable contacts located within said cavity, an insulating closure member 75 substantially closing the opening leading into said ing outwardly from said closure member, said cavity, a guide located partly within said cavity guide having a. portion in line with said movable and projecting through said closure member and contact and being movably carried by said body together with said closure member closing said portion, whereby said guide is efi'ective to addicavity, and an operating member for said movtionally operate said movable contact. able contact carried by said guide and project- EARL F. MEKELBURG. 

